bpf_helpers - add more const annotations
Keys and values passed in to lookup/update/delete are not modified.
Test: builds
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I222615af7695f41bfb59c872c7368829631c08a9
diff --git a/progs/include/bpf_helpers.h b/progs/include/bpf_helpers.h
index e933021..454db2d 100644
--- a/progs/include/bpf_helpers.h
+++ b/progs/include/bpf_helpers.h
@@ -29,43 +29,51 @@
*
* This defines the map (hence this should not be used in a header file included
* from multiple locations) and provides type safe accessors:
- * ValueType * bpf_foo_map_lookup_elem(KeyType *)
- * int bpf_foo_map_update_elem(KeyType *, ValueType *, flags)
- * int bpf_foo_map_delete_elem(KeyType *)
+ * ValueType * bpf_foo_map_lookup_elem(const KeyType *)
+ * int bpf_foo_map_update_elem(const KeyType *, const ValueType *, flags)
+ * int bpf_foo_map_delete_elem(const KeyType *)
*
* This will make sure that if you change the type of a map you'll get compile
* errors at any spots you forget to update with the new type.
+ *
+ * Note: these all take 'const void* map' because from the C/eBPF point of view
+ * the map struct is really just a readonly map definition of the in kernel object.
+ * Runtime modification of the map defining struct is meaningless, since
+ * the contents is only ever used during bpf program loading & map creation
+ * by the bpf loader, and not by the eBPF program itself.
*/
-static void* (*bpf_map_lookup_elem_unsafe)(void* map, void* key) = (void*)BPF_FUNC_map_lookup_elem;
-static int (*bpf_map_update_elem_unsafe)(void* map, void* key, void* value,
+static void* (*bpf_map_lookup_elem_unsafe)(const void* map,
+ const void* key) = (void*)BPF_FUNC_map_lookup_elem;
+static int (*bpf_map_update_elem_unsafe)(const void* map, const void* key, const void* value,
unsigned long long flags) = (void*)
BPF_FUNC_map_update_elem;
-static int (*bpf_map_delete_elem_unsafe)(void* map, void* key) = (void*)BPF_FUNC_map_delete_elem;
+static int (*bpf_map_delete_elem_unsafe)(const void* map,
+ const void* key) = (void*)BPF_FUNC_map_delete_elem;
/* type safe macro to declare a map and related accessor functions */
#define DEFINE_BPF_MAP_NO_ACCESSORS(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
- struct bpf_map_def SEC("maps") the_map = { \
+ const struct bpf_map_def SEC("maps") the_map = { \
.type = BPF_MAP_TYPE_##TYPE, \
.key_size = sizeof(TypeOfKey), \
.value_size = sizeof(TypeOfValue), \
.max_entries = (num_entries), \
};
-#define DEFINE_BPF_MAP(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
- DEFINE_BPF_MAP_NO_ACCESSORS(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
- \
- static inline __always_inline __unused TypeOfValue* bpf_##the_map##_lookup_elem( \
- TypeOfKey* k) { \
- return bpf_map_lookup_elem_unsafe(&the_map, k); \
- }; \
- \
- static inline __always_inline __unused int bpf_##the_map##_update_elem( \
- TypeOfKey* k, TypeOfValue* v, unsigned long long flags) { \
- return bpf_map_update_elem_unsafe(&the_map, k, v, flags); \
- }; \
- \
- static inline __always_inline __unused int bpf_##the_map##_delete_elem(TypeOfKey* k) { \
- return bpf_map_delete_elem_unsafe(&the_map, k); \
+#define DEFINE_BPF_MAP(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
+ DEFINE_BPF_MAP_NO_ACCESSORS(the_map, TYPE, TypeOfKey, TypeOfValue, num_entries) \
+ \
+ static inline __always_inline __unused TypeOfValue* bpf_##the_map##_lookup_elem( \
+ const TypeOfKey* k) { \
+ return bpf_map_lookup_elem_unsafe(&the_map, k); \
+ }; \
+ \
+ static inline __always_inline __unused int bpf_##the_map##_update_elem( \
+ const TypeOfKey* k, const TypeOfValue* v, unsigned long long flags) { \
+ return bpf_map_update_elem_unsafe(&the_map, k, v, flags); \
+ }; \
+ \
+ static inline __always_inline __unused int bpf_##the_map##_delete_elem(const TypeOfKey* k) { \
+ return bpf_map_delete_elem_unsafe(&the_map, k); \
};
static int (*bpf_probe_read)(void* dst, int size, void* unsafe_ptr) = (void*) BPF_FUNC_probe_read;